Throughout the specification, a term MPEG is generally used as a generic reference to a family of international standards set by the Motion Picture Expert Group. MPEG reports to subcommittee 29 (SC29) of the Joint Technical Committee (JTC1) of the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC).
Throughout the specification, a term H.26x is generally used as a generic reference to a closely related group of international recommendations by the Video Coding Experts Group (VCEG). VCEG addresses Question 6 (Q.6) of Study Group 16 (SG16) of the International Telecommunications Union Telecommunication Standardization Sector (ITU-T). The standards/recommendations specify exactly how to represent visual and audio information in a compressed digital format. The standards/recommendations are used in a wide variety of applications, including DVD (Digital Video Discs), DVB (Digital Video Broadcasting), digital cinema, and videoconferencing.
Throughout the specification, a term MPEG/H.26x will generally refers to the superset of MPEG and H.26x standards and recommendations. Several major MPEG/H.26x standards exist, such as H.261, MPEG-1, MPEG-2/H.262 and MPEG-4/H.263. Among the standards, MPEG-2/H.262 is commercially significant, being sufficient in many applications for all the major television standards, including NTSC (National Standards Television Committee) and HDTV (High Definition Television). Of the series of MPEG standards that describe and define the syntax for video broadcasting, the standard of relevance to the present invention includes the standard ITU-T Recommendation H.264, ISO/IEC 14496-10 AVC, which is hereinafter referred to as “MPEG-AVC/H.264”.
A feature of MPEG/H.26x is that the standards are often capable of representing a video signal with data roughly 1/50th a size of the original uncompressed video, while still maintaining good visual quality. Although the compression ratio varies greatly depending on the nature of the detail and motion of the source video, the example compression ratio serves to illustrate that compressing digital images is an area of interest to those who provide digital transmission.
MPEG/H.26x achieves high compression of a video signal through the successive application of four basic mechanisms:    1) Storing the luminance (e.g., black and white) detail of the video signal with more horizontal and vertical resolution than the two chrominance (e.g., color) components of the video.    2) Storing only the changes from one video frame to another, instead of the entire frame. Stored motion vector symbols indicate spatial correspondence between frames.    3) Storing the changes with reduced fidelity, as quantized transform coefficient symbols, to trade off a reduced number of bits per symbol with increased video distortion.    4) Storing all the symbols representing the compressed video with entropy encoding, to reduce the number of bits per symbol without introducing any additional video signal distortion.